Are you planning on doing something special with it (like turning it into a restaurant or shop)? I'd put it on the cliff at the bottom of the map, the one between the ramp below the Cafe and that villager's house.
I like the little space on the bottom where the land curves out by the beach access. That or on the top half right above where the river turns into the lake area. The little peninsula's are always cute but that villager that's at the opening of it would be right in front of it. (By peninsula I mean the little squarish area outlined by your river)